How parthenocarpic fruits are formed

Parthenocarpy is the natural or artificially induced production of fruit without fertilization of ovules, which makes the fruit seedless. Stenospermocarpy may also produce apparently seedless fruit, but the seeds are actually aborted while they are still small. Parthenocarpy (or stenospermocarpy) occasionally occurs as a mutation in nature; if it affects every flower the plant can no longer sexually reproduce but might be able to propagate by apomixis or by vegetative means. In some plants, pollination or another stimulation is required for parthenocarpy, termed stimulative parthenocarpy. Plants that do not require pollination or other stimulation to produce parthenocarpic fruit have vegetative parthenocarpy. Seedless cucumbers are an example of vegetative parthenocarpy, seedless watermelon is an example of stenospermocarpy.So  these fruits are formed without fertilization'.